NissenFundoplication

Prepare patient Divide peritoneum Divide short gastricsExpose crura and

GE junctionWrap fundus CloseRepair crura

DividePull fundus

underAnchorfundus

JoinSuturewrap

Elevateesophagus

Locate Locate Locate LocateDivide Divide

Slipgrasperunder

LiftGraspfundus

Transfergrasp

Pull acrossInsert

endostitchSuture Knot Cut suture Suture Knot Cut suture

Reach andorient

Grasp andhold / cut

Push Pull Release

Switch tool

Hierarchical Decomposition of Minimally Invasive Surgery:A Valuable Research and Investigative Tool

MacKenzie, C.L., Ibbotson, J.A., Cao, C.G.L. & Lomax, A.J., Simon Fraser University, Canada

AcknowledgementsThanks to the surgeons, O.R. staff, and patients. Thanks to E. Lee, S. Manske, and B. Zheng.

Funded by British Columbia Health Research Foundation (BCHRF) and Institute for Robotics and Intelligent Systems (IRIS), Canada.

What surgical steps are difficult and take time?Note the time to wrap fundus is shortened when the short gastrics are cut

Where is the surgeon looking?Analysis of gaze patterns: on the monitor, down on hands, away

Total Number of Motions for Suturing (both tools)

0

2

4

6

810

12

14

16

18

reach & orient grasp & hold/cut push pull release

Motion

Fre

quen

cy

normal suture

anchor suture

What motions are performed most often during suturing?Reaching and orienting

4. Results

1. Background Complex activities break down to progressively smaller units

(Miller, Galanter & Pribram, 1960)

Human factors, task analysis, user-task-tool

2. Purpose1. To study the surgeon as the user of the technology in a complex

human-machine system

2. To decompose minimally invasive surgery hierarchically

3. Method Videotape laparoscopic procedures:

- cholecystectomies (n = 4)

- inguinal hernia repairs (n = 4)

- Nissen fundoplications (n = 9)

Define events e.g., tool entries, gaze shift, goal attainment

Develop hierarchical decomposition

Operationally define beginnings and endings of:

- surgical steps

- substeps

- tasks

- subtasks

- tool motions

Annotate videotapes and perform analyses on the timing of events.

5. Discussion Hierarchical decomposition can be used to:

1. Evaluate surgeons’ performance

2. Design training for surgery e.g., with augmented or virtual environments

Modular sections correspond to our procedural breakdown

3. Evaluate surgeons’ learning

4. Design and evaluate effectiveness of new tools

5. Evaluate different aspects of O.R. layout e.g., monitor display position

6. Preoperative planning of patient-specific surgery

7. Analyze surgeons’ focus of attention at different levels of the hierarchy

8. Improve safety and decrease errors

9. Make a better “fit” between technology and the surgeon.

6. ReferencesCao, C.G.L., MacKenzie, C.L., Ibbotson, J.A., Turner, L.J., Blair, N.P. and Nagy, A.G. (1999).

Hierarchical decomposition of laparoscopic procedures. In Westwood, J.D., Hoffman, H.M., Robb, R.A., & Stredney, D. (Eds.), The convergence of physical and informational technologies: Options for a new era in healthcare. (MMVR: 7). Amsterdam: IOS Press, 83-89.

Ibbotson, J.A., MacKenzie, C.L., Cao, C.G.L., and Lomax, A.J. (1999). Gaze patterns in laparoscopic surgery. In Westwood, J.D., et al. (Eds.) The convergence of physical and informational technologies: Options for a new era in healthcare. (MMVR: 7). Amsterdam: IOS Press, 154-160.

MacKenzie, C.L., Ibbotson, J.A., Cao, C.G.L. and Lomax, A.J. (1998). Intelligent tools for minimally invasive surgery: Safety and error issues. In Proceedings of Enhancing patient safety and reducing errors in health care. Chicago: National Patient Safety Foundation, 226-229.

Miller, G.A., Galanter, E., and Pribram, K.H. (1960). Plans and the structure of behavior. New York: Henry Holt and Co.

Duration of Fundoplication Surgical Steps

05

10152025303540

prepare patient divideperitoneum

expose cruraand EG junction

repair crura divide shortgastrics

wrap fundus

Surgical Step

Dura

tion

(m

inut

es)

No Division

Divide Short Gastrics